Mitochondrial DNA in evolution and disease

Cellular organelles called mitochondria contain their own DNA. The discovery that variation in mitochondrial DNA alters physiology and lifespan in mice has implications for evolutionary biology and the origins of disease. See Letter p.561 José Antonio Enríquez and colleagues look into the effects of mitochondrial DNA sequence variation by using congenic mice strains that share the same nuclear genome, but have different mitochondrial DNA. They show that the mitochondrial genome has a profound influence on many aspects of physiology — including insulin signalling, obesity and telomere shortening — and results in differences in median lifespan. Thus non-pathological mitochondrial DNA variants have a broad effect on metabolism, with the differences more pronounced later in life. The authors suggest that the interplay of mitochondrial and nuclear genomes may be an important factor influencing this phenomenon, which may have implications for the field of mitochondrial replacement.